Positive temperature coefficient (PTC) of resistance heating elements are small ceramic stones with self-regulating temperature properties. Such heating elements can be utilized, for example, in heating systems. In a heating system, PTC thermistors can be placed between, and thermally coupled to, a pair of electrode plates in order to transfer heat.
Related patents known in the art include the following: U.S. Pat. No. 4,972,067, issued to Lokar et al. on Nov. 20, 1990, discloses a PTC heater assembly and a method of manufacturing the heater assembly. International Published Patent Application WO 99/18756, filed by Golan et al. on Oct. 1, 1998, discloses an immersible PTC heating device.